| 摘要 |
<p>An apparatus and method for detecting a short circuit in a load which receives power from a transformer wherein the transformer has a primary winding and a secondary winding and wherein the load is connected to the secondary winding. The apparatus comprises a waveform conversion circuit for converting voltage and current signals that represent the voltage and current, respectively, of the primary winding into generally squarewave voltage and current signals, respectively. The apparatus further comprises a phase detector circuit for outputting a control signal having a first state when the generally squarewave voltage and current signals are substantially in phase and a second state when there is in a difference in phase between the generally squarewave voltage and current signals that is greater than a predetermined phase difference. The apparatus further comprises a filter for filtering the signal outputted by the phase detector circuit. In one embodiment, the apparatus further comprises a circuit for deactivating the load when the control signal has the second state. In one embodiment, the apparatus and method of the present invention are used to detect a short in a lighting system that receives power from a transformer that has a primary winding and a secondary winding wherein the load is connected to the secondary winding.</p> |
